1. Field of the Invention
The present invention relates to an apparatus for dispensing sealant material of a liquid crystal display device, and more particularly, to an apparatus for dispensing sealant material of a liquid crystal display device in which a washing processing is not required. According to the present invention, poor quality of a cell gap because of debris (foreign object) can be effectively prevented by using a disposable syringe.
2. Discussion of the Related Art
In general, a liquid crystal display device is a display device in which a data signals according to image information are individually provided to liquid crystal cells disposed in a matrix to adjust a light transmissivity of the liquid crystal cells, and accordingly desired images can be displayed.
In general, the liquid crystal display device includes a liquid crystal display panel on which liquid crystal cells in a pixel unit are disposed in a matrix and a driver integrated circuit (IC) for driving the liquid crystal cells.
The liquid crystal display panel typically includes a color filter substrate and a thin film transistor array substrate that face each other, and a liquid crystal layer positioned between the color filter substrate and the thin film transistor array substrate.
A plurality of data lines for transmitting data signals provided from a data driver IC to the liquid crystal cells are orthogonal to a plurality of gate lines for transmitting scan signals provided from the gate driver IC to the liquid crystal cells on the thin film transistor array substrate of the liquid crystal display panel. The liquid crystal cells are defined at crossings between those data lines and gate lines.
The gate driver IC provides the scan signal in sequence to the plurality of gate lines to allow the liquid crystal cells disposed in the matrix to be sequentially selected for each gate line, and the liquid crystal cells of the one selected gate line receive a data signal from the data driver IC.
On the other hand, a common electrode and a pixel electrode are provided respectively at each facing inner surface of the color filter substrate and the thin film transistor array substrate to apply an electric field to the liquid crystal layer. A pixel electrode is positioned at the thin film transistor array substrate of each liquid crystal cell, while the common electrode is formed at a front surface of the color filter substrate. Therefore, the light transmissivity of the liquid crystal cells can individually be adjusted by controlling a voltage applied to the pixel electrode in when a voltage has been applied to the common electrode.
Thus, in order to control the voltage applied to the pixel electrode by a liquid crystal cell, each liquid crystal cell is provided with a thin film transistor as a switching device.
Those components of the aforementioned liquid crystal display device will be explained in detail with reference to the accompanying drawings as follows.
FIG. 1 is an exemplary view showing a schematic plan view of a unit liquid crystal display panel for which a thin film transistor array substrate and a color filter substrate of a liquid crystal display device face each other and are attached.
Referring to FIG. 1, a liquid crystal display panel 100 includes an image display unit 113 on which liquid crystal cells are disposed in a matrix, a gate pad unit 114 connected to gate lines of the image display unit 113, and a data pad unit 115 connected to data lines. Here, the gate pad unit 114 and the data pad unit 115 are formed at edge areas of a thin film transistor array substrate 101 in an area that does not overlap with a color filter substrate 102. The gate pad unit 114 provides a scan signal provided by a gate driver integrated circuit (IC) to the gate lines of the image display unit 113, while the data pad unit 115 provides image information (e.g., data signals) provided by the data driver IC to the data lines of the image display unit 113.
The data lines to which the image information is applied and the gate lines to which the scan signal is applied are arranged to perpendicularly cross each other at the thin film transistor array substrate 101 of the image display unit 113. The thin film transistor array substrate 101 include: a thin film transistor positioned at crossings between the data lines and the gate lines for switching liquid crystal cells; a pixel electrode connected to the thin film transistor for driving the liquid crystal cells; and a protection film formed at a front surface thereof for protecting the electrode and the thin film transistor.
The color filter substrate 102 of the image display unit 113 includes color filters separated by a black matrix according to a cell region and coated thereon, and a transparent common electrode which is a counter electrode of the pixel electrode positioned at the thin film transistor array substrate 101.
Such a thin film transistor array substrate 101 and the color filter substrate 102 maintain a predetermined cell gap by a spacer and are attached by a seal line 116 positioned at an outside of the image display unit 113, thereby forming a unit liquid crystal display panel.
In fabricating such unit liquid crystal display panel, a method for forming a plurality of unit liquid crystal display panels simultaneously on a large aperture mother substrate may be used in order to improve yield. Therefore, a processes for cutting and processing the mother substrate on which the plurality of liquid crystal display panels have been fabricated and thus separating the unit liquid crystal display panels from the large aperture mother substrate are required.
In the unit liquid crystal display panel separated from the large aperture mother substrate, a liquid crystal layer is positioned between the thin film transistor array substrate 101 and the color filter substrate 102 by injecting liquid crystal through a liquid crystal injection opening. Afterwards, the liquid crystal injection opening is encapsulated.
As described above, in order to fabricate the unit liquid crystal display panel, are various processes are required, including a process for individually fabricating a plurality of thin film transistor array substrates 101 and color filter substrates 102 at separate first and second mother substrates, and another process for attaching the first and second mother substrates to maintain a uniform cell gap, and a process for cutting it into unit liquid crystal display panels, thereafter injecting liquid crystal.
In particular, in order to attach the first and second mother substrates to maintain the uniform cell gap, a process for forming a seal line 116 at an outside of the image display unit 113 is required. Here, the method for forming the seal line 116 of the related art will be described in detail with reference to drawings.
FIGS. 2A and 2B are exemplary views illustrating a screen printing method for forming a seal line. As illustrated in FIGS. 2A and 2B, a screen printing apparatus includes a screen mask 206 patterned to allow a region for forming a seal line 216 to be selectively exposed and a squeegee 208 for selectively supplying a sealant 203 onto a substrate 200 through the screen mask 206 and forming the seal line 216.
The seal line 216 formed on the substrate 200 arranges a gap to inject liquid crystal thereinto and prevents leakage of the injected liquid crystal. Therefore, the seal line 216 is positioned along edges of the image display unit 213 of the substrate 200, and a liquid crystal injection opening 204 is located at a certain side of the seal line 216.
Thus, the screen printing method includes a step of forming the seal line 216 on the substrate 200 by depositing the sealant 203 over the screen mask 206 at which a region for forming the seal line 216 has been patterned and printing it with the squeegee 208; and a step of drying the seal line 216 by evaporating a solvent contained in the seal line 216 and leveling it.
The screen printing method has an excellent convenience of processes and therefore has been generally used. However, the sealant consumption is disadvantageously high because of forming the seal line 216 by depositing the sealant 203 over a front surface of the screen mask 206 and printing it with the squeegee 208.
Further, since the screen mask 206 is in contact with the substrate 200, a rubbing defect could occur in an alignment layer (not shown) positioned on the substrate 200, which causes a degradation of image quality of a liquid crystal display device.